Bonded Segmented Slips

ABSTRACT

A slip assembly for a downhole tool, such as a bridge plug, has a slip body composed of independent segments. The segments are affixed together along their longitudinal sides by a bond, which can be composed of thermoplastic or thermoset resins, an elastomer, epoxy adhesives, bonding agent manufactured using ceramic, metallic agent, or a combination of these. The surface area over which the bonding agent is applied can be controlled for a particular implementation. Thus, more or less of the longitudinal sides of the segments can be bonded to other segments. This provides greater control of the required force to break the bond itself, which can be tailored as desired.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Appl. 61/789,467, filed 15 Mar. 2013, which is incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

Slips are used for various downhole tools, such as bridge plugs and packers. The slips can have inserts or buttons to grip the inner wall of a casing or tubular. Examples of downhole tools with slips and inserts are disclosed in U.S. Pat. Nos. 6,976,534 and 8,047,279.

For example, FIG. 1A illustrates a downhole tool 10 having slip assemblies 20 according to one type in the prior art. FIG. 1B illustrates a detailed view of the prior art slip assembly of FIG. 1A. The tool 10 is a bridge plug composed mainly of composite material. The bridge plug 10 has a mandrel 12 on which the slip assemblies 20, cones 14, and extrusion rings 16 fit on either side of a sealing element 18.

As shown, the slip assemblies 20 each comprise a number of independent segments 22 disposed about the mandrel 12. The segments 22 are composed of non-metallic material, such as composite, and use inserts 24 to engage with the casing to stop the plug 10 from moving during its operation. The inserts 24 are typically made from cast or forged metal, which is then machined and heat-treated to the proper engineering specifications according to conventional practices. When the bridge plug 10 is being set, the slip segments 22 are pushed toward the ramped surfaces of the cones 14 so that the segments 22 move away from the mandrel 12 and engage against a surrounding tubular or casing wall.

To hold the various segments 22 together during run-in of the bride plug, bands 26 are disposed in grooves around the top and bottom ends of the segments 22. The bands 26 hold the segments 22 inward together around the mandrel 12 and yield when the segments move away from the mandrel 12 by pushing against the cones 14. The bands 26 can be composed of metal, plastic, or the like. Care must be taken when running-in the tool that the bands 26 do not break, which would allow the segments 22 to fall free of the mandrel 12 and hinder operation of the plug 10.

Rather than using bands to hold the segments together, the slip assemblies 20 for a downhole tool can having various segments integrally connected together. For example, FIG. 2A illustrates a detailed view of another type of slip assembly 30 according to the prior art. Here, the slip assembly 30 is shown relative to a cone 14 for use on a downhole tool, such as a bridge plug discussed previously. The assembly has a number of segments that dispose about the tool's mandrel (not shown). Rather than being independent segments requiring securement by a separate band or the like, the segments 32 have interconnecting portions or joints 36 integrally formed between the segments.

The slip assembly 30 can be composed of composite or other material by molding or the like, and the joints can be machined in assembly 30. When the assembly 30 is pushed against the ramped surface of the cone 14, the segments 32 break at the joints 36 so that the segments 32 can then act to independently wedge between the cone 14 and the surrounding casing wall (not shown).

Rather than such an extensively machined notch, the slip assembly 30 in FIG. 2B has a similar arrangement of integrally connected segments 32, but these segments are connected at their ends by an integral end ring portion 38. In any event, this assembly 30 can operate similar to that discussed above in FIG. 2A.

As can be seen above, non-metallic slip segments 22 used in downhole tools 10, such as composite fracture plugs, are held together by independent yield bands disposed around the segments 22 or by a notch or other interconnecting portion between each segment 22. Although these assemblies may be effective, there are still drawbacks.

The yield bands can be composed of metal to hold the composite slip segments together. This introduces metallic components to a downhole tool, which is undesirable for fracture plugs and the like due to longer mill-up time. Yield bands composed of non-metallic material may not have the required mechanical properties to hold the slip segments together while tripping the tool 10 downhole.

The notch introduces inconsistent results due to variations in material properties, manufacturing processes, etc. In addition, the process in which the notch fractures or breaks during setting of the tool can compromise structural integrity of the composite slip segments and the inserts 24 held therein.

The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a downhole tool having slip assemblies according to one type in the prior art.

FIG. 1B illustrates a detailed view of the prior art slip assembly of FIG. 1A.

FIG. 2A illustrates a detailed view of another type of slip assembly according to the prior art.

FIG. 2B illustrates a detailed view of a similar prior art slip assembly to that shown in FIG. 2A.

FIG. 3A illustrates a downhole tool having slip assemblies according to the present disclosure.

FIG. 3B illustrates a detailed side view of the slip assembly in FIG. 3A.

FIG. 3C illustrates a detailed cross-sectional view of the slip assembly in FIG. 3A.

FIG. 4 illustrates a detailed side view of another slip assembly according to the present disclosure.

FIG. 5A illustrates slip segments 52 bonded to a mandrel using bonding material.

FIG. 5B illustrates ends of slip segments bonded to a setting shoulder (e.g., ring or mule-shoe) of a tool using bonding material.

FIG. 5C illustrates other ends of slip segment bonded to a cone of a tool using bonding material.

FIG. 6 illustrates a slip assembly of the present disclosure including a number of metallic slip segments.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 3A illustrates a downhole tool 10 having slip assemblies 50 according to the present disclosure. The downhole tool 10 can be a bridge plug as shown, but it could also be a packer, a liner hanger, an anchoring device, or other downhole tool.

The tool 10 has a mandrel 12 having cones 14 and backup rings 16 arranged on both sides of a packing element 18. Outside the inclined cones 14, the tool 10 has slip segments 52. Together, the slip segments 52 along with the cones 14 can be referred to as the slip assemblies 50, or in other instances, just the slip segments 52 may be referred to as the slip assemblies 50. In either case, either reference may be used interchangeably throughout the present disclosure.

As shown herein, the slip segments 52 have inserts or buttons 54. As a bridge plug, the tool 10 is preferably composed mostly of non-metallic components according to procedures and details as disclosed, for example, in U.S. Pat. No. 7,124,831, which is incorporated herein by reference in its entirety. This makes the tool 10 easy to mill out after use.

When deployed downhole, the plug 10 is activated by a wireline setting tool (not shown), which uses conventional techniques of pulling against the mandrel 12 while simultaneously pushing upper components against the slip assembly 50. As a result, the slip segments 52 ride up the cones 14, the cones 14 move along the mandrel 12 toward one another, and the packing element 18 compresses and extends outward to engage a surrounding casing wall. The backup elements 16 control the extrusion of the packing element 18. The slip segments 52 are pushed outward in the process to engage the wall of the casing, which both maintains the plug 10 in place in the casing and keeps the packing element 18 contained. The metallic inserts 54 in the non-metallic slip segments 52 allow the assemblies 50 to sufficiently grip the inside of the casing.

The force used to set the plug 10 may be as low as 30,000 lbf. and could be as high as 85,000 lbf. These values are only meant to be examples and could vary for the size of the tool. In any event, once set, the plug 10 isolates upper and lower portions of the casing so that frac and other operations can be completed uphole of the plug 10, while pressure is kept from downhole locations. When used during frac operations, for example, the plug 10 may isolate pressures of 10,000 psi or so.

As shown in FIGS. 3B-3C, the segments 52 of the assemblies 50 are each independent segments. Rather than being independently held by yield bands or interconnected by integrally formed joints, the segments 52 are held by a bond between each longitudinal side of the segments 52. The bonded slip segments 52 can separate from one another when expanded by the cones 14 to get more consistent results while not degrading the mechanical integrity of the slip segments 52.

The slip segments 52 can be bonded using a bonding material, such as a thermoplastic resin, a thermoset resin, an elastomer, an epoxy adhesive, and a bonding agent manufactured using ceramic, graphite, metallic agent, or a combination of these. Some examples include high temperature ceramic and graphite adhesives and high performance epoxies, such as those available from Aremco. Additional examples include metal filled epoxies, such as Duralco™ 4540, which is an active aluminum filled epoxy available from Cotronics Corporation, or include a high-temperature adhesive, such as Durabond 950, which is a metallic ceramic composite available from Cotronics Corporation. The surface area over which the bonding agent is applied can be controlled for a particular implementation. Thus, more or less of the longitudinal sides of the segments 52 can be bonded to other segments 52. This provides greater control of the required force to break the bond itself, which can be tailored as desired.

Again, bonding the slip segments 52 together with thermoplastic or thermoset resins or a bonding agent manufactured out of ceramics, metallic agents, etc. . . . results in a tighter control over break strength of the slip segments 52. The bonds 56 are independent of the mechanical properties of the slip segments 52. This allows the material properties of the bonds 56 to be different from the material of the slip segments 52. In this sense, the bond 56 can be configured to have an appropriate break strength without compromising the integrity of the segments 52 when the bond 56 breaks. The bonding agent can be designed to fracture and break apart a predetermined stress, thus allowing the slip segments 52 to retain their structural integrity.

To form a slip assembly 50 as disclosed herein, a plurality of independent segments 52 are formed using standard practices, such as molding, machining, etc. As noted above, the segments 52 can be made of a non-metallic material and can have one or more inserts 54 disposed in the outward surface of the segments 52.

The segments 52 are then disposed side-by-side about a mandrel 12 of a downhole tool 10 so that one end of the segments 52 are adjacent the ramped end of a cone 14 on the mandrel 12. Each of the adjacent sides of the segments 52 are bonded with a bonding material that affixes the independent segments 52 as a unit together around the mandrel 12. As noted above, the bonding material can be a thermoplastic resin, a thermoset resin, an elastomer, an epoxy adhesive, a bonding agent manufactured using ceramic agent, a bonding agent manufactured using a metallic agent, and a bonding agent manufactured using a combination of ceramic and metallic agent.

Depending on the bonding material and how it can be applied, bonding the adjacent sides of the segments 52 with the bonding material can be done by applying the bonding material to the adjacent sides of the segments 52 before or after they are disposed side-by-side about the mandrel 12. For example, the bonding material can be applied to one or more sides of the segments 52, and the segments 52 can then be placed in or on a fixture so that the bonding material cures to affix the sides together. Once set, the affixed segments 52 can be disposed as a unit on the mandrel 12 of the tool 10. Alternatively, the segments 52 with the bonding material already applied can be placed around the mandrel 12 and held by a fixture until cured in place on the mandrel 12 of the tool 10.

In yet another alternative, the segments 52 can be disposed in place about the mandrel 10, and the bonding material can be applied to the exposed sides between the gaps or separations between the segments 52 to affix the sides together. As will be appreciated, temporary fixtures may be used to hold the segments 52 in place while the bonding material cures or otherwise hardens. Once the slip assembly 50 is assembled separately (i.e. bonded using a fixture), the assembly 50 can then be placed on the mandrel. (Finally, the backup elements 16 of FIG. 3A used to control the extrusion of the packing element 18 can also be bonded together in the same way as done with slip segments 52.)

FIG. 4 shows another slip assembly 50 according to the present disclosure. The segments 52 of the assemblies 50 are each independent segments. Here, yield bands 60 are disposed around the segments 52 to hold them against the tool's mandrel. The bands 60 can fit in external slots (not visible) defined in the outer surfaces of the segments 50 both above and below the inserts 54. The yield bands 60 are composed of band segments 62 bonded together with bonds 64 to form the ring structure of the bands 60. In general, each band 60 can having one or more band segments 62 that form at least a portion of a ring. Ends of the band segments 62 are bonded together with the bonding material to form the band 60.

The band segments 62 can be composed of metal. In this case, use of the bonds 64 between segments 62 can still reduce the overall metallic content of the tool. This will also provide for faster mill up times because the segments 62 will break up easier than a solid ring during milling. Alternatively, the band segments 62 can be composed of a non-metallic material. Although such material may be millable or the like, it need not necessarily have a required yield strength. Instead, the characteristics of the material used for the bonds 64 can be particularly configured to provide the needed breaking or yield to the bands 60 when the slip segments 52 are pushed against the cone 14.

The bands 60 can fit in lateral slots on the outside surfaces of the segments 52. The bands 60 can be fully or partially constructed and then disposed about the segments, or the bands 60 can be constructed on the segments 52 disposed in its circular arrangement.

In addition to or instead of bonding the slip segments 52 to one another, FIGS. 5A-5C show alternative arrangements where the slip segments 52 are bonded to a component of the downhole tool. In FIG. 5A, the slip segments 52 are bonded to the mandrel 12 using bonding material 70. Each of the slip segments 52 can be separately bonded to the mandrel 12 and may have free gaps 55 between their long sides. In FIG. 5B, ends of the slip segments 52 are bonded to a setting shoulder 13 (e.g., ring or mule-shoe) of the tool using bonding material 72. In FIG. 5C, the other ends of the slip segments 52 are bonded to the cone 14 of the tool using bonding material 74. The bonding of the slip segments 52 in each of these can be combined together in any desired manner, and the slip segments 52 can be bonded to one another.

As can be seen in FIGS. 5A-5C, bonding the slip segments 52 to the mandrel 12, setting shoulder 13 (e.g., ring or mule-shoe), cone 14, or any combination of these together can provide a means of slip retention on the tool. Of course, if desired, the sides of the segments 52 can also be bonded in a manner similar to previous embodiments.

Finally, as shown in FIG. 6, a slip assembly 50 of the present disclosure can include a number of metallic slip segments 52. Each segment 52 can comprise several smaller pieces 58 that are bonded together by bonding material 57 to form a unitary slip segment 52. In turn, these segments 52 can be bonded together side-by-side using another bonding material 56 to form one complete slip assembly 57. The bonding material 56 used along the sides of the segments 52 may be relatively weaker than the bonding material 57 used for the segment's pieces 58. This arrangement would also reduce mill-up time because the slip segments 52 comprised of bonded pieces 58 are expected to break up easier than single homogenous segments.

For the embodiments disclosed herein, additional components may be used in conjunction with the bonding to retain the slip segments 52 in place especially during run-in. For example, pins (not shown) may be used to pin the slip segments 52 to the mandrel 12. Alternatively, solid bands (not shown) or other external feature may be used on the segments 52 and may even be glued in place to hold the segments 52 to the mandrel 12. As will be appreciated, these and other additional components can be used to enhance retention of the segments 52 or at least to provide a failsafe during run-in of the tool 10.

Embodiments disclosed herein have illustrated the cones 14 as has having flat ramps so that the segments 52 have comparably configured ramped ends. As will be appreciated, this geometry is not strictly necessary because the cones 14 and segments' ends can have any suitable geometry (e.g., conical, flat ramp, etc.). Moreover, any number of slip segments 52 can be used depending on the implementation.

The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter.

In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof. 

What is claimed is:
 1. A downhole apparatus, comprising: a plurality of segments being independent from one another and being disposed side-by-side about the downhole apparatus, each side of the segments bonded by bonding material to the side of an adjacent one of the segments, wherein the segments separate from one another at the bonded sides when expanded outward from the downhole apparatus.
 2. The apparatus of claim 1, wherein at least a portion of each of the segments is bonded by bonding material to a component of the downhole apparatus.
 3. The apparatus of claim 1, further comprising a cone disposed on the downhole apparatus adjacent one end of the segments, the cone and the segments being moveable relative to one another to expand the segments radially outward from the downhole apparatus.
 4. The apparatus of claim 3, further comprising a mandrel of the downhole tool about which the cone and the segments are positioned.
 5. The apparatus of claim 1, wherein the bonding material is selected from the group consisting of a thermoplastic resin, a thermoset resin, an elastomer, an epoxy adhesive, a bonding agent manufactured using ceramic agent, a bonding agent manufactured using a metallic agent, a bonding agent manufactured using a graphite agent, and a bonding agent manufactured using a combination of ceramic and metallic agents.
 6. A method of forming a slip assembly on a downhole tool, the method comprising: forming a plurality of independent segments; positioning the segments side-by-side about the downhole tool; and bonding each side of the segments with bonding material to the side of an adjacent one of the segments.
 7. The method of claim 6, further comprising bonding at least a portion of each of the segments with bonding material to a component of the downhole apparatus.
 8. The method of claim 6, wherein the bonding material is selected from the group consisting of a thermoplastic resin, a thermoset resin, an elastomer, an epoxy adhesive, a bonding agent manufactured using ceramic agent, a bonding agent manufactured using a metallic agent, and a bonding agent manufactured using a combination of ceramic and metallic agents.
 9. The method of claim 6, wherein bonding each side of the segments with bonding material to the side of the adjacent one of the segments comprises applying bonding material to the adjacent sides of the segments before or after positioning the segments side-by-side about the mandrel.
 10. A downhole apparatus, comprising: a plurality of segments being independent from one another and being disposed side-by-side about the downhole apparatus, at least one retaining element disposed about the segments and holding the segments adjacent the downhole apparatus, the at least one retaining element having one or more components with ends affixed together by bonding material, wherein the bonded ends of the one or more components separate from one another when the segments expand outward from the downhole apparatus.
 11. The apparatus of claim 10, wherein each segment comprises a surface disposed between the sides of the segment and facing outward away from the downhole apparatus, the surface defining a slot in which the retaining element disposes.
 12. The apparatus of claim 10, wherein the one or more components of the retaining element each comprise at least a portion of a ring composed of a non-metallic material.
 13. The apparatus of claim 10, wherein at least a portion of each of the segments is bonded by bonding material to a component of the downhole apparatus.
 14. The apparatus of claim 10, wherein sides of the segments are bonded by bonding material to the sides of adjacent ones of the segments.
 15. The apparatus of claim 10, further comprising a cone disposed on the downhole apparatus adjacent one end of the segments, the cone and the segments being moveable relative to one another to expand the segments radially outward from the downhole apparatus.
 16. The apparatus of claim 15, further comprising a mandrel of the downhole tool about which the cone and the segments are positioned.
 17. The apparatus of claim 10, wherein the bonding material is selected from the group consisting of a thermoplastic resin, a thermoset resin, an elastomer, an epoxy adhesive, a bonding agent manufactured using ceramic agent, a bonding agent manufactured using a metallic agent, and a bonding agent manufactured using a combination of ceramic and metallic agents.
 18. A downhole apparatus, comprising: a component of the downhole apparatus; a plurality of segments being independent from one another and being disposed side-by-side about the downhole apparatus, at least a portion of each of the segments bonded by bonding material to the component of the downhole appartaus, wherein the segments separate from one another and separate at the bonded portions when expanded outward from the downhole apparatus.
 19. The apparatus of claim 18, wherein the component of the downhole apparatus comprises a cone disposed on the downhole apparatus, the portion of each of the segments bonded by bonding material to the cone, the segments separating from one another and separating at the bonded portions when expanded outward from the downhole apparatus by the cone.
 20. The apparatus of claim 18, wherein the component of the downhole apparatus comprises a mandrel of the downhole apparatus about which the segments are disposed, the portion of each of the segments bonded by bonding material to the mandrel, the segments separating from one another and separating at the bonded portions when expanded outward from the mandrel.
 21. The apparatus of claim 18, wherein the component of the downhole apparatus comprises a setting shoulder of the downhole apparatus adjacent which the segments are disposed, the portion of each of the segments bonded by bonding material to the setting shoulder, the segments separating from one another and separating at the bonded portions when expanded outward from the downole apparatus.
 22. The apparatus of claim 18, wherein sides of the segments are bonded by bonding material to the sides of adjacent ones of the segments.
 23. A method of forming a slip assembly on a downhole tool, the method comprising: forming a plurality of independent segments; positioning the segments side-by-side about the downhole tool; and bonding at least a portion of each of the segments to a component of the downhole tool with bonding material.
 24. The method of claim 23, wherein the bonding material is selected from the group consisting of a thermoplastic resin, a thermoset resin, an elastomer, an epoxy adhesive, a bonding agent manufactured using ceramic agent, a bonding agent manufactured using a metallic agent, and a bonding agent manufactured using a combination of ceramic and metallic agents.
 25. The method of claim 23, wherein bonding the portion of each of the segments to the component of the downhole tool with bonding material comprises applying bonding material before or after positioning the segments side-by-side about the downhole tool.
 26. The method of claim 23, wherein the component of the downhole apparatus comprises a cone disposed on the downhole apparatus, and wherein bonding the portion of each of the segments comprises bonding the portion of each of the segments to the cone of the downhole tool with bonding material.
 27. The method of claim 23, wherein the component of the downhole apparatus comprises a mandrel of the downhole apparatus about which the segments are disposed, and wherein bonding the portion of each of the segments comprises bonding the portion of each of the segments to the mandrel of the downhole tool with bonding material.
 28. The method of claim 23, wherein the component of the downhole apparatus comprises a setting shoulder of the downhole apparatus adjacent which the segments are disposed, and wherein bonding the portion of each of the segments comprises bonding the portion of each of the segments to the setting shoulder of the downhole tool with bonding material. 